Plunger operated reed relay switch

ABSTRACT

The invention relates to a plunger operated reed relay switch module that incorporates a novel permanent magnet and mounting for the magnet which permits the plunger which operates the magnet to have the same travel characteristics as a plunger which actuates the contacts in a plunger operated snap switch. The switch module thus may be used as a replacement for a snap switch in a device when the device is required to control the input signals in a solid state logic circuit.

United States Patent Wrabetz [4 1 July 11, 1972 [54] PLUNGER OPERATEDREED RELAY 3,613,038 10/1971 Bell ..200/67 F x SWITCH 3,621,415 11/1971Bell ..200/67FX [72] Inventor: Voyta E. Wrabetz, Hubertus, Wis. PrimaryExaminer Bemard A Gilheany [73] Assignee: Square D Company, Park Ridge,111. Assistant Examiner-R. N. Envall, Jr. [22] Filed: July 14 1971Attorney-Harold J. Rathbun et a1.

[21] Appl. No.2 162,496 [57] ABSTRACT The invention relates to a plungeroperated reed relay switch U.S. 67 F module that incorporates a novelpeflnanent magnet and [51] Int. Cl. ..H0lh 5/00 mounting f the magnetwhich permits the plunger which [58] Field of Search ..335/205, 206,207; 200/67 F operates the magnet to have the same travelcharacteristics as a plunger which actuates the contacts in a plungeroperated [56] References Cited snap switch. The switch module thus maybe used as a replace- UNITED STATES PATENTS ment for a snap switch in adevice when the device is required 7 to control the input signals in asolid state logic circuit. 3,423,705 1/1969 Cherry et a1 ..200/67 F X3,611,219 10/1971 lwami ..200/67 F X 10 Claims,6Draw1ngfigures PatentedJuly 11, 1972 mwe F. 3% 1W ||1 F INVENTOR.

' VOYTA E. WRABETZ PLUNGER OPERATED REED RELAY SWITCH This inventionrelates to reed relay switch modules and is more particularly concernedwith a plunger operated reed relay switch module which is especiallysuited to be used as a substitute for a plunger operated snap switch ina device which is required to control a solid state circuit.

A dry reed switch is a well known device that comprises a pair ofresilient metal reeds which extend axially into an evacuated tube fromopposite ends thereof with their tip portions overlapping in the medialportion of the tube and laterally spaced apart by a small distance. Thereeds are magnetically permeable; hence when a magnet field is caused tothread both of the reeds and the gap between the reeds, the tip portionsof the reeds are magnetically attracted and the reeds flex into switchclosing engagement with each other.

It has been long appreciated that reed switches possess many desirablecharacteristics that adapt them for use in applications involvinghostile environments and low voltage and current circuits as may bepresent in solid state logic circuits. However, reed switches also arefragile and while they are capable of reliably making and interruptinglow voltage and current circuits, they are incapable of controllinglarger currents as are required by devices, such as limit switches,which are used in control circuits of solenoids, control relays andmotor starters which control the motion of machine tools, conveyors andpractically every type of motor driven machine.

One form of a limit switch, as shown in U.S. Pat. No. Re. 27,016, whichwas reissued on Dec. 29, 1970 to Rudolf H. Kiessling and Carl A.Schaeffer, includes a housing wherein one or more plunger operated snapswitches are included and an external operator which operates theplungers of the snap switches. While the limit switch in the Kiesslinget al. patent has been successfully used in typical limit switchcircuits, it is not particularly suited for use in solid state circuitsbecause the contacts in the snap switches are susceptible to oxidationand are not designed to operate in circuits having currents and voltagespresent in solid state circuits.

While it is possible to design a limit switch which has an operatingmechanism expressly designed to operate a reed switch, a more economicalapproach is to provide a limit switch which is capable of operating botha snap switch and/or a reed switch, so the same limit switch may readilybe converted to a control conventional limit switch circuit and/or asolid state circuit. This result is achieved by providing a reed switchmodule, as will be hereinafter described, which has the same operatingcharacteristics as a snap switch so the reed switch module may besubstituted for the snap switch in a limit switch or other device whichis conventionally used to actuate a snap switch in a manner well knownto those skilled in the art.

It is an object of the present invention to provide a reed switch modulewhich may be substituted for a plunger operated snap switch in aswitching device.

An additional object is to provide a reed switch module with a magnetstructure which will have a concentrated magnetic field and a pivotmounting which will permit a plunger, which controls the movement of themagnet, to have the same travel characteristics as a plunger operatedsnap switch.

A further object is to provide a reed switch module with a housing thatencloses a reed switch and a permanent magnet and provides a guide for amovable plunger which, when moved between two positions in the housing,causes an arched portion on the magnet to swing between two positionsrelative to a contact gap portion of the reed switch.

Another object is to provide a reed switch module with a permanentmagnet that has side walls of opposite polarity extending between twoopposite ends of the magnet and to provide an archway at one of the endsof the magnet, which receives the envelope of a reed, so the magneticfield between the side walls is concentrated by the archway.

Further objects and features of the invention will be readily apparentto those skilled in the art from the following specification and fromthe appended drawings illustrating certain preferred embodiments, inwhich:

FIG. 1 is a front plan view of a plunger operated reed switch moduleincorporating the features of the present invention.

FIGS. 2 and 3 are front views of the switch module in FIG. 1 with acover portion of the module removed and respectively showing theinternal components of the module when the plunger is in a deactuatedposition and an actuated position.

FIG. 4 is an exploded view showing in perspective the operatingcomponents of the switch in FIGS. 2 and 3.

FIGS. 5 and 6 are respectively a side and a front view of a permanentmagnet used in the module in FIGS. 2 and 3.

A switch module 10, shown in the drawing, includes a housing 12 and acover 14 which are formed of a molded insulating material and define aninternal cavity 16. The housing 12 has a pair of apertured ears 18extending outwardly from a lower wall 20 and a passage 22 extendinginwardly through a top wall 24 into the cavity 16. The ears 18 areprovided so the module 10 may be mounted in a device or on a support,not shown, and the passage 22 provides a guide for a plunger 26. Theplunger 26 is movable within the passage 22 and includes a portion 28that is movable within the cavity 16 and a portion 30 that extendsexternally of the top wall 24. Positioned within the cavity 16, andextending through suitable openings in the cover 14, are three brassterminal members 32, 34 and 36, each of which has a strip-like shape.The terminal member 32 is positioned at the lower left-hand corner ofthe cavity 16 adjacent a left side wall 38 of the housing 12 by aprojection 40. The projection 40 extends forwardly in the cavity 16 froma rear wall 42 portion of the housing 12. The terminal members 34 and 36are positioned adjacent a right side wall 44 of the housing 12respectively at the upper and lower right hand corners of the-cavity 16by a projection 46 which extends forwardly from the rear wall 42. Theprojections 40 and 46 have front surfaces spaced forwardly from the rearwall 42.

A commercially available reed switch 48 is positioned within the cavity16 adjacent the rear wall 42 and includes a sealed glass envelope 50,preferably filled with an inert gas. A pair of reeds 52 and 54, whichact as stationary contacts for the reed switch 48, extend into theinterior of the envelope 50 from the right end of the envelope 50. Thereeds 52 and 54 are not required to be flexible and respectively havetip portions 56 and 58 located at a medial portion of the envelope 50and are connected to terminal members 60 and 62 respectively at theright end of the envelope 50. The terminal members 60 and 62 haveportions positioned upon the front surface of the projection 46 and havetheir respective ends secured, as by welding, to the terminal members 34and 36 respectively. The tip portions 56 and 58 are spaced from eachother and are respectively located adjacent the upper and the lowerinner side walls of the envelope 50. The reed 52 is formed of anonmagnetically permeable material and the reed 54 is formed of amagnetically permeable material. The reed switch 48 additionallyincludes a flexible reed 64 of magnetically permeable material thatextends into the interior of the envelope 50 from the left end of theenvelope 50. The reed 64 extends from a tip portion 66 which is locatedin the space between tip portions 56 and 58 so as to overlap slightlywith either of the tip portions 56 or 58 to a terminal member 68 whichhas a portion positioned on the front surface of the projection 40 andan end secured, as by welding, to the terminal member 32. The reed 64 ispreloaded so that the tip portion 66 normally engages the tip portion 56and is flexible so that the tip portion 66 will move into engagementwith the tip portion 58 in response to a magnet field which threads thereeds 54 and 64 and the gap between the tip portions 58 and 66.

A permanent magnet assembly 70, which is pivotally movable within thecavity 16, includes a magnet metal part 72 and a magnet holder 74. Themagnet holder 74 is preferably formed of a suitable plastic material,such as nylon, and includes a recess wherein the magnet part 72 securedas by an adhesive, so that the magnet part 72 and the magnet holder 74effectively act as a unitary part within the cavity 16.

The magnet part 72 and the magnet holder 74 are shaped so the magnetassembly 70 has a pair of opposite side walls 76 and 78 extendingparallel to each other between a lower end 80 and an upper end 82 of themagnet assembly 70. The end 80 has a U-shaped archway 84 extendingbetween the side walls 76 and 78 and a portion of the side wall adjacentthe end 82 has a groove 86 which receives a pivot pin 88 to pivotallymount the magnet assembly 70 in the cavity 16. The magnet part 72 ispolarized so the side walls 76 and 78 have opposite magnet polarities.The pivot pin 88 is immovably positioned by the housing 12 and extendsfrom the rear wall 42 in the cavity 16 so that the envelope 50 of thereed switch 48 is received in the archway 84 when the pivot pin 88 isreceived in the pivot groove 86. The pin 88 is located so the medialportion of the envelope 50 is centered in the archway 84 when the magnetassembly 70 is positioned as in FIG. 2 and is displaced from the archway84 when the magnet assembly 70 is at the osition shown in FIG. 3. Themagnet assembly is also provided with an actuating surface 90 on theside 78 that is adjacent the end 82 which is constantly engaged by anapex 91 on a resilient finger 92 to maintain the pin 88 in the groove86.

As previously described, the reed switch 48 is positioned adjacent therear wall 42 of the cavity 16. The portion 28 of the plunger is movablein a space in the cavity 16 located between the reed switch 48 and theinner surface of the cover 14. The portion 28 has a bore, not shown,extending upwardly from a bottom end 94 which receives a portion of aspring 96. The spring 96, which has an end positioned on the lower wall20, biases the plunger 26 upwardly in the housing 12. The upwardmovement of the plunger 26 is limited by a stop portion 98 on the leftside of the portion 28 which engages a stop surface 100 on the top wall24. The right side of the portion 28 is provided with verticallyextending recess 102 and a surface 104 adjacent the bottom end 94 whichhas a circular boss 106 projecting from the surface 104. The resilientfinger 92 is formed of a flexible metal to have a strip-like shape andincludes an opening 108 at its lower end which receives the boss 106 andthe apex 91 at its upper end which engages the surface 90 on the magnetassembly 70. The finger 92 is maintained in an assembled position on theportion 28 of the plunger so as to be movable in the recess 102 bypositioning a lower portion of the finger 92 on the surface 104 with theboss 106 received in the opening 108 and ultrasonically staking the freeend of the boss 106 over the surface portions of the finger 92.

The switch module is assembled by positioning the envelope 50 in thearchway 84 and inserting the components of a sub-assembly consisting ofthe reed switch 48, the terminal members 60, 62 and 68 and the terminalmembers 32, 34 and 36 within the cavity 16 with the envelope 50positioned within the archway 84 while the groove 86 is positioned onthe pivot pin 88. A sub-assembly, including the plunger 26, theresilient finger 92 and the spring 96, is then positioned in the cavity16. The assembly of the switch module 10 is completed when the cover 14is secured on the open front of the housing 12 by a suitable screw, notshown, which passes through an opening 112. The screw has a threadedposition received in an opening in a rear surface of the cover 14 and aheaded portion engaging a rear surface on the rear wall 42.

The switch module 10 is shown in FIG. 2 in its deactuated conditionwherein the spring 96 causes the plunger to be moved to a positionwherein the stop surfaces 98 and 100 are engaging and the apex 91 ispositioned above a horizontal plane passing through the pivot pin 88.The engagement between the apex 91 and the actuating surface 90 willposition the magnet assembly 70 so that the side wall 78 engages thesurface 104 and the archway 84 is positioned at the medial portion ofthe envelope 50 whereat the tips 56, 58 and 66 are located. When themagnet assembly 70 is positioned as in FIG. 2, the magnet flux fieldbetween the side walls 76 and 78 will be concentrated within the archway84 and will pass through the magnet metal reeds 54 and 64 as well as thegap between the tip portions 58 and 66. The magnet flux through the gapbetween the tip portions 58 and 66 causes the tip portions 58 and 66 tohave opposite magnetic polarities and the tip portion 66 to move intoengagement with the tip portion 58. When the tip portions 58 and 66 areengaging, an electric circuit is completed between the terminal 32 andthe terminal 36.

The switch module 10 is actuated when an external force applies to theplunger 26, against the spring return force provided by the spring 96,causes the plunger 26 to move into a housing 12 to the position shown inFIG. 3. The movement of the plunger 26 from the position shown in FIG. 2to the position shown in FIG. 3, causes the apex 91 to move across theactuating surface from a position where the apex 91 is above thehorizontal plane through the pin 88 to a position where the apex 91 isbelow the horizontal plane. The movement of the apex 91 across theactuating surface 90 will cause the magnet assembly 70 to swing in acounterclockwise direction to a position whereat a portion of the magnetassembly 70 engages a fixed stop 114 on the housing. When the magnetengages the stop 114, the archway 84 and the magnet field in the archway84 will be displaced relative to the medial portion of the envelope 50so that the tip 66 is no longer magnetically attracted toward the tip58. The reed 64 thus is free to move, and because of its prestressedcondition, causes the tip 66 to engage the tip 56 and a circuit betweenthe terminal 32 and the terminal 34 to be completed.

One of the advantages embodied in the switch module 10 is that thedistance between the pivot pin 88 and the apex 91 is substantially lessthan the distance between the pivot pin 88 and the archway 84 so that asmall movement of the apex 91 across the actuating surface 90 will causea large swinging motion of the end of the permanent magnet carrying thearchway 84. Thus only a small movement of the plunger 26 is required tocause the archway 84 to swing to its displaced position relative to themedial portion of the envelope 50. After the magnet assembly 70 is movedinto engagement with the stop 114, a continued motion of the plunger 26will be without effect as the resilient finger 92, which is biasedtoward the magnet assembly 70, causes the magnet assembly 70 to remainin engagement with the stop 114 so that the movement of the plunger 26may be continued after the magnet assembly 70 has moved to itsdeactuated position. Thus the operation of the switch module 10 can bemade to resemble that of a conventional snap switch which requiresconsiderable plunger travel to actuate the switch contacts.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the art and the invention is to be given its broadestpossible interpretation within the terms of the following claims.

What is claimed is:

l. A switch module comprising: a switch housing having an internalcavity, a permanent magnet pivotally mounted within the cavity, saidpermanent magnet having: opposite side walls of opposite magneticpolarity extending between two opposite ends, an archway extendingbetween the side walls at a first of the two ends, a pivot portion at asecond of the two ends pivotally mounting the magnet on the housing sothat the first end is swingably movable between two positions in thecavity, and an actuating portion at the second end, a reed switchincluding: an elongated tubular envelope and a pair of magneticallypermeable electrically conducting reeds extending axially in theenvelope to provide a pair of engageable contact tip portions at themedial portion of the envelope, means for mounting the reed switchwithin the cavity so that the medial portion is received in the archwayand a magnetic flux is induced in said pair of reeds when the first endof the magnet is at a first of its two positions and the archway andmedial portion are displaced relative to each other when the first endof the magnet is at a second of its two positions, and a plunger havingan operating portion engaging the actuating portion on the magnet, saidoperating portion being movable between two positions in the cavity formoving the first end of the magnet to the first of its two positionswhen the operating portion is at one of its two positions and for movingthe first end of the magnet to the second of its two positions when theoperation portion is at a second of its two positions.

2. A switch module comprising: a switch housing having an internalcavity, a permanent magnet pivotally mounted within the cavity, saidpermanent magnet having: opposite side walls of opposite magneticpolarity extending parallel to each other between two opposite ends ofthe magnet, an archway extending between the side walls at a first oftwo ends, a pivot groove at a second of the two ends extending parallelto the side walls, and an actuating portion at the second end of themagnet, a pin carried by the housing and received in the pivot groovefor mounting the magnet in the cavity so the first end is swingablymovable between two positions in the cavity, a reed switch including: anelongated tubular envelope, a magnetic permeable conductive contactmember fixed to a first end of the envelope and extending axiallythereinto, a magnetically permeable resiliently flexible reed mounted ata second end of the envelope and extending axially thereinto, said reedand contact member extending into the envelope to provide a pair ofcontact tip portions which are in overlapping relationship at the medialportion of the envelope and normally spaced apart when the reed is at afirst position and said reed being flexible so that the reed is flexedtoward the contact member to move the tip portions into engagement whena magnetic flux is induced in the reed and the contact member and thereed is at a second position, means for mounting the reed switch in thecavity so the envelope is received in the archway during the swingingmovement of the first end of the magnet and for positioning the medialportion so the magnet flux is induced in the reed and contact member andthe reed is flexed to its second position when the first end of themagnet is at a first of its two positions and so that the archway andmedial portion are displaced and the reed and contact member are intheir normally spaced apart positions and the reed is at its firstposition when the first end of the magnet is at a second of its twopositions, and a plunger having an operating portion engaging theactuating portion on the magnet, said operating portion being movablebetween two positions in the cavity for moving the first end of themagnet to the first of its two positions when the operating portion isat one of its two positions and for moving the first end of the magnetto the second of its two positions when the operating portion is at asecond of its two positions.

3. The switch module as recited in claim 1 wherein the reed switchincludes an additional contact member that is nonmagnetically permeableand includes a tip portion that is engaged by the tip portion on thereed when the reed is at its first position.

4. The switch module as recited in claim 1 wherein the operating portionon the plunger is provided by a resilient member.

5. The switch module as recited in claim 1 wherein the distance betweenthe archway and the pivot portion is greater than the distance betweenthe actuating portion and the pivot portion.

6. The switch module as recited in claim 4 wherein the pivot portion andthe actuating portion are disposed on opposite sides of the magnet, thepivot portion is provided by a groove extending in one of the side wallsand a pin which is supported by the housing and received in the groove,and the resilient member engages the actuating portion and maintains thepin within the groove during movements of the magnet to its twopositions.

7. The switch module as recited in claim 6 wherein the resilient membermaintains the pin in the groove when the plunger is moved beyond one ofits two positions.

8. The switch module as recited in claim 7 wherein the plunger ismovable along a linear path in the housing, a spring biases the plungerto a first of its two positions, the magnet is at its first positionwhen the plunger is at its first position and is moved with a swingingmovement about its pivot portion to its second position when the plungeris moved to a second of its two positions.

9. The switch module as recited in claim 1 wherein the archway isU-shaped.

10. The switch module as recited in claim 9 wherein the pivot portionand the actuating portion are disposed on opposite sides of the magnet,the pivot portion 15 provided by a groove extending in one of the sidewalls and a pin which is supported by the housing and received in thegroove, and the resilient member engages the actuating portion andmaintains the pin within the groove during movements of the magnet toits two positions.

1. A switch module comprising: a switch housing having an internalcavity, a permanent magnet pivotally mounted within the cavity, saidpermanent magnet having: opposite side walls of opposite magneticpolarity extending between two opposite ends, an archway extendingbetween the side walls at a first of the two ends, a pivot portion at asecond of the two ends pivotally mounting the magnet on the housing sothat the first end is swingably movable between two positions in thecavity, and an actuating portion at the second end, a reed switchincluding: an elongated tubular envelope and a pair of magneticallypermeable electrically conducting reeds extending axially in theenvelope to provide a pair of engageable contact tip portions at themedial portion of the envelope, means for mounting the reed switchwithin the cavity so that the medial portion is received in the archwayand a magnetic flux is induced in said pair of reeds when the first endof the magnet is at a first of its two positions and the archway andmedial portion are displaced relative to each other when the first endof the magnet is at a second of its two positions, and a plunger havingan operating portion engaging the actuating portion on the magnet, saidoperating portion being movable between two positions in the cavity formoving the first end of the magnet to the first of its two positionswhen the operating portion is at one of its two positions and for movingthe first end of the magnet to the second of its two positions when theoperation portion is at a second of its two positions.
 2. A switchmodule comprising: a switch housing having an internal cavity, apermanent magnet pivotally mounted within the cavity, said permanentmagnet having: opposite side walls of opposite magnetic polarityextending parallel to each other between two opposite ends of themagnet, an archway extending between the side walls at a first of twoends, a pivot groove at a second of the two ends extending parallel tothe side walls, and an actuating portion at the second end of themagnet, a pin carried by the housing and received in the pivot groovefor mounting the magnet in the cavity so the first end is swingablymovable between two positions in the cavity, a reed switch including: anelongated tubular envelope, a magnetic permeable conductive contactmember fixed to a first end of the envelope and extending axiallythereinto, a magnetically permeable resiliently flexible reed mounted ata second end of the envelope and extending axially thereinto, said reedand contact member extending into the envelope to provide a pair ofcontact tip portions which are in overlapping relationship at the medialportion of the envelope and normally spaced apart when the reed is at afirst position and said reed being flexible so that the reed is flexedtoward the contact member to move the tip portions into engagement whena magnetic flux is induced in the reed and the contact member and thereed is at a second position, means for mounting the reed switch in thecavity so the envelope is received in the archway during the swingingmovement of the first end Of the magnet and for positioning the medialportion so the magnet flux is induced in the reed and contact member andthe reed is flexed to its second position when the first end of themagnet is at a first of its two positions and so that the archway andmedial portion are displaced and the reed and contact member are intheir normally spaced apart positions and the reed is at its firstposition when the first end of the magnet is at a second of its twopositions, and a plunger having an operating portion engaging theactuating portion on the magnet, said operating portion being movablebetween two positions in the cavity for moving the first end of themagnet to the first of its two positions when the operating portion isat one of its two positions and for moving the first end of the magnetto the second of its two positions when the operating portion is at asecond of its two positions.
 3. The switch module as recited in claim 1wherein the reed switch includes an additional contact member that isnonmagnetically permeable and includes a tip portion that is engaged bythe tip portion on the reed when the reed is at its first position. 4.The switch module as recited in claim 1 wherein the operating portion onthe plunger is provided by a resilient member.
 5. The switch module asrecited in claim 1 wherein the distance between the archway and thepivot portion is greater than the distance between the actuating portionand the pivot portion.
 6. The switch module as recited in claim 4wherein the pivot portion and the actuating portion are disposed onopposite sides of the magnet, the pivot portion is provided by a grooveextending in one of the side walls and a pin which is supported by thehousing and received in the groove, and the resilient member engages theactuating portion and maintains the pin within the groove duringmovements of the magnet to its two positions.
 7. The switch module asrecited in claim 6 wherein the resilient member maintains the pin in thegroove when the plunger is moved beyond one of its two positions.
 8. Theswitch module as recited in claim 7 wherein the plunger is movable alonga linear path in the housing, a spring biases the plunger to a first ofits two positions, the magnet is at its first position when the plungeris at its first position and is moved with a swinging movement about itspivot portion to its second position when the plunger is moved to asecond of its two positions.
 9. The switch module as recited in claim 1wherein the archway is U-shaped.
 10. The switch module as recited inclaim 9 wherein the pivot portion and the actuating portion are disposedon opposite sides of the magnet, the pivot portion is provided by agroove extending in one of the side walls and a pin which is supportedby the housing and received in the groove, and the resilient memberengages the actuating portion and maintains the pin within the grooveduring movements of the magnet to its two positions.